NiO Nanoparticle Synthesis Using a Triblock Copolymer: Enhanced Magnetization and High Specific Capacitance of Electrodes Prepared from the Powder.

Nickel oxide nanoparticles of diameter ∼21 nm were prepared by a sol-gel method using the triblock copolymer poly(ethylene glycol)--(propylene glycol)--(ethylene glycol). X-ray photoelectron spectroscopy analysis showed the presence of Ni and Ni ions in the material. The electrical conductivity of this material was due to small polaron hopping between Ni and Ni sites. The magnetization shown by these nanoparticles was much higher than that reported in the literature. This is ascribed to the presence of Ni ions with uncompensated spin moments. Spin-glass behavior was exhibited by the material at 10.7 K. The electrochemical characterization of electrodes comprising of these NiO nanoparticles using cyclic voltammetric measurements showed a specific capacitance value of 810 F/g, the highest reported for this material. These materials will thus form one of the useful multifunctional systems.